The paranasal sinuses comprise four separate pairs of three-dimensional (3D) air-filled spaces which are in proximity to the nasal cavity. Invasive surgery of a selected region of the sinuses may be considered necessary, for example, in the case of severe sinusitis, using a catheter to reach the region. Typically, at present, prior to performing such invasive surgery, a computerized tomography (CT) scan of a selected region of one of the sinuses and its environs is taken. A physician analyzes the scan in order to select the best path, typically the shortest path, from a nostril to the selected region to be taken by the catheter.
The selection of the best path is not a trivial operation. The sinuses are 3D spaces, and, especially if there is any sort of blockage between a nostril and the selected region, the best path may comprise a relatively complicated route. In addition, while the CT scan can be used to generate 3D images, the analysis of such images, because they are three-dimensional, is difficult and time-consuming.
U.S. Pat. No. 7,720,521 to Chang et al., whose disclosure is incorporated herein by reference, describes a system for performing image guided interventional and surgical procedures, including various procedures to treat sinusitis and other disorders of the paranasal sinuses.
U.S. Pat. No. 8,160,676 to Gielen et al., whose disclosure is incorporated herein by reference, describes a method for planning a surgical procedure. The plan can include a path or trajectory to reach a selected target.
US Patent Application 2008/0183073, issued as U.S. Pat. No. 9,037,215 on May 19, 2015, to Higgins et al., whose disclosure is incorporated herein by reference, describes methods to assist in planning routes through hollow, branching organs in patients to optimize subsequent endoscopic procedures.
U.S. Pat. No. 8,116,847 to Gattani et al., whose disclosure is incorporated herein by reference, describes a method for calculating an optimum surgical trajectory or path for displacing a surgical instrument through the interior of the body of a patient.
Documents incorporated by reference in the present patent application are to be considered an integral part of the application except that, to the extent that any terms are defined in these incorporated documents in a manner that conflicts with definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.